1. Field of the Invention
The invention relates to an apparatus, a method, and a system for detecting an attachment of e-mail for macro viruses.
2. Description of the Prior Art
With the recent prevalence of PCs and the Internet, information exchange by means of e-mail is growing in use. It is often the case now that ones with evil intent hide viruses in attachments of e-mail so that users unaware of it open the attachments to let the viruses invade their PCs. Such viruses are called macro viruses since they adhere to certain application software and infect upon the execution of the software procedure. When macro viruses invade a PC, document files may be tampered with arbitrarily or an unintended screen may appear during system startup.
When a number of PCs, such as corporate PCs, are connected over a LAN, a number of PCs can be exposed to virus attack at a time.
Among the known methods for protecting a computer system from such computer viruses is one using so-called vaccines. Vaccines are a kind of dedicated software, containing a database that defines the patterns of viruses found and reported so far. Upon virus invasion, the vaccines collate the pattern of the virus with the patterns of the viruses stored in the database to identify the invading virus.
The foregoing virus inspection using vaccine software, however, has the problem that it is effective against known viruses but hardly effective against unknown viruses. In addition, the database must be modified each time a new type of virus is found and reported. This requires that the vaccine users constantly update the vaccine software for data renewal. Moreover, such vaccine software is dependent on the computer OS (Operating System), having a problem of unavailability on different OSes.